Generally, an original from which copies are to be made by a silver salt type copying machine is classified into two groups. The first group contains printed originals and photographic originals, and the original is classified into this group by determining the materials contained on the original. The second group contains high contrast originals and half tone originals, and the original is classified into this group by determining the image quality of the original. Regarding the first group of originals, because of the use of inks contained in the printed originals and of dyes contained in the photographic originals, the printed and photographic originals have different spectral reflection densities. Regarding the second group of originals, the high contrast originals often include letters and line drawings in which contrast is considered to be important. In the half tone originals, gradation is considered to be important.
Although originals have different image characteristics, the silver salt type of copying apparatus conventionally uses the same type of photosensitive material for copying all of the different types of originals. As a result, poor quality copies result for various types of originals.